1. Field of the Invention
The present invention relates to a light source device, and a display device and a television receiver therewith.
2. Description of the Related Art
A light source device used for a liquid-crystal display device or an illuminated sign, as described in JP-A-2001-67008, is conventionally known, which includes light sources, a translucent optical member opposite to the light sources, and a reflector plate disposed on the opposite side of the light sources from the optical member so as to reflect light to the optical member side.
In this kind of the light source device, if light from the light sources is directly radiated to the optical member, the close-to-light-source areas of the optical member are very brightly illuminated, while the areas distant from the light sources are poorly illuminated. This could result in forming so-called lamp images on the optical member. If the lamp images are thus formed, the brightness of the screen of the liquid-crystal display device lacks uniformity, which has undesirable effects on visual quality.
For this reason, in the light source device according to JP-A-2001-67008, a thin film having patterns formed of a light-reflective material is applied to the optical-member-side surface of the light sources. Thereby, light radiated from the light sources to the optical member side is partly reflected by the patterns formed on the thin film, while light transmitted through the unpatterned areas directly illuminates the optical member. Consequently, the amount of light radiated from the light sources directly to the optical member can be decreased. The light reflected by the patterns is, together with light radiated from the light sources to the opposite side of the optical member, reflected by the reflector plate, so as to indirectly illuminate the optical member. Thus, the amount of light directly radiated to the optical member is decreased, while the amount of light reflected by the reflector plate and indirectly illuminating the optical member is increased. Thereby, formation of lamp images can be suppressed.
In recent years, as for the above light source device used for a liquid-crystal display device, enhancement of luminescence per light source and thereby reduction in the total number of light sources have been required for reduction in cost and the number of components. Specifically, a hot-cathode tube has a luminescence intensity approximately several times higher than that of a cold-cathode tube conventionally used for a liquid-crystal display device, or more. Thereby, the total number of the light sources can be reduced almost to a third or a sixth, compared to the case in which cold-cathode tubes are used.
In the light source device according to the above-described construction, light radiated from the light sources to the front side and transmitted through the unpatterned areas directly illuminates the optical member. Therefore, in the case that the above-described hot-cathode tubes are used as light sources, the unpatterned areas can function as high-intensity light sources, and thereby lamp images having shapes corresponding to the patterns formed on the thin film may be formed on the optical member.